The present invention relates to a method for preparing a hot-bonding silicone adhesive composition which does not develop tack or adhesiveness at room temperature upon the removal of organic solvent but which does develop a high adhesive strength upon heating.
Silicone adhesives have an excellent tack, adhesive strength, pressure-sensitive adhesive strength, etc., at ambient temperatures. In addition, their properties such as heat resistance, cold resistance, electrical properties, etc., are those characteristic of silicones. As a consequence, they are widely used for electrical insulating tape, where a high level of reliability is essential, and in adhesives and various pressure-sensitive adhesives where thermal stability and cold resistance are critical.
As a general matter, these silicone adhesive compositions take the form of organoperoxide-curing compositions consisting of the mixture of dimethylsiloxane gum and methylpolysiloxane resin. A separate impulse in this regard are compositions which are cured by platinum-type catalysts and consist of mixtures of alkenyl group-containing diorganopolysiloxane plus organohydrogenpolysiloxane plus organopolysiloxane resin. However, the preceding adhesive compositions in each case evidence a strong tack and a high adhesive or pressure-sensitive adhesive strength at room temperature. Thus, when coated on the surface of various substrates in the production of tape-form adhesives, the problem arises that the coated surface and the back surface of the tape substrate will adhere to one another and cannot be peeled apart. A release treatment of the back surface of the tape substrate is therefore necessary in order to provide such a tape on a practical basis. Also, when a sheet-form adhesive is stacked up during storage after manufacture, it is necessary to insert a separation or release material between the adhesive-coated surface and the sheet-form substrate.